cpu/saml21: Fix possibly uninitialized variable in pm.c.
cpu/saml21: Fix possibly uninitialized variable in pm.c.

mtausig/RIOT,BytesGalore/RIOT,smlng/RIOT,x3ro/RIOT,mtausig/RIOT,gebart/RIOT,ant9000/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,yogo1212/RIOT,kYc0o/RIOT,avmelnikoff/RIOT,ant9000/RIOT,toonst/RIOT,rfuentess/RIOT,ant9000/RIOT,biboc/RIOT,kYc0o/RIOT,avmelnikoff/RIOT,avmelnikoff/RIOT,BytesGalore/RIOT,mtausig/RIOT,aeneby/RIOT,josephnoir/RIOT,biboc/RIOT,x3ro/RIOT,OlegHahm/RIOT,toonst/RIOT,avmelnikoff/RIOT,authmillenon/RIOT,basilfx/RIOT,kbumsik/RIOT,basilfx/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,smlng/RIOT,jasonatran/RIOT,jasonatran/RIOT,jasonatran/RIOT,kbumsik/RIOT,aeneby/RIOT,neiljay/RIOT,josephnoir/RIOT,lazytech-org/RIOT,kaspar030/RIOT,aeneby/RIOT,BytesGalore/RIOT,lazytech-org/RIOT,kaspar030/RIOT,miri64/RIOT,OTAkeys/RIOT,mtausig/RIOT,neiljay/RIOT,OlegHahm/RIOT,rfuentess/RIOT,authmillenon/RIOT,basilfx/RIOT,authmillenon/RIOT,cladmi/RIOT,biboc/RIOT,yogo1212/RIOT,kbumsik/RIOT,kbumsik/RIOT,OTAkeys/RIOT,kaspar030/RIOT,lazytech-org/RIOT,biboc/RIOT,authmillenon/RIOT,smlng/RIOT,yogo1212/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,smlng/RIOT,neiljay/RIOT,cladmi/RIOT,miri64/RIOT,cladmi/RIOT,ant9000/RIOT,authmillenon/RIOT,toonst/RIOT,jasonatran/RIOT,gebart/RIOT,kaspar030/RIOT,miri64/RIOT,OTAkeys/RIOT,A-Paul/RIOT,OlegHahm/RIOT,gebart/RIOT,ant9000/RIOT,miri64/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,A-Paul/RIOT,rfuentess/RIOT,cladmi/RIOT,x3ro/RIOT,yogo1212/RIOT,cladmi/RIOT,mfrey/RIOT,basilfx/RIOT,mfrey/RIOT,OlegHahm/RIOT,yogo1212/RIOT,josephnoir/RIOT,neiljay/RIOT,OlegHahm/RIOT,biboc/RIOT,A-Paul/RIOT,neiljay/RIOT,OTAkeys/RIOT,x3ro/RIOT,toonst/RIOT,A-Paul/RIOT,aeneby/RIOT,BytesGalore/RIOT,mfrey/RIOT,kYc0o/RIOT,smlng/RIOT,A-Paul/RIOT,miri64/RIOT,yogo1212/RIOT,aeneby/RIOT,BytesGalore/RIOT,x3ro/RIOT,OTAkeys/RIOT,mfrey/RIOT,josephnoir/RIOT,mtausig/RIOT,avmelnikoff/RIOT,basilfx/RIOT,gebart/RIOT,josephnoir/RIOT,jasonatran/RIOT,gebart/RIOT,rfuentess/RIOT,rfuentess/RIOT,RIOT-OS/RIOT,mfrey/RIOT,lazytech-org/RIOT,toonst/RIOT,lazytech-org/RIOT,kbumsik/RIOT